The main goal of this project is to study the population biology of transposable genetic elements (parasites of the genome) using Drosophila as a model system in conjunction with quantitative theoretical analysis. During this period, the research has focused on two topics: 1) What is the primary mechanism containing the numbers of transposable elements? and 2) Is the evolutionary diversity observed between copies of elements at the DNA sequence level consistent with quantitative models of the dynamics of the elements in natural populations? Work over the last several years in this laboratory have led to the hypothesis that unequal crossing over is an important mechanism in the containment of transposable elements. The theoretical analysis of this model were examined. Ongoing research concerns the rate of occurrence of such events. A large number of spontaneous chromosomal deletions have been collected and the breakpoints are being characterized at the DNA sequence level to confirm the role of crossing over between transposable elements. The cloning and DNA sequencing of copies of the transposable element hobo from sampled individuals, populations and species is ongoing.